ASP.Net SQL Server sql injection safety

gistfile1.txt

Dim connString As String = ConfigurationManager.ConnectionStrings("your_database").ConnectionString
Dim sqlString As String = ""
Dim sqlConnection As New SqlConnection(connString)
 
sqlString = "insert into [ss].[dbo].[MyGuestBook] (firstName) values (@firstName);"
Dim sqlCommand As New SqlCommand(sqlString, sqlConnection)
 
Dim paramFirstName = New SqlParameter("firstName", SqlDbType.VarChar)
paramFirstName.Value = inputFromUserCleanedFirstName
sqlCommand.Parameters.Add(paramFirstName)
 
sqlConnection.Open()
sqlCommand.ExecuteScalar()